U.S. patent number 4,897,771 [Application Number 07/125,323] was granted by the patent office on 1990-01-30 for reflector and light system.
This patent grant is currently assigned to Lumitex, Inc.. Invention is credited to Jeffrey R. Parker.
United States Patent |
4,897,771 |
Parker |
January 30, 1990 |
Reflector and light system
Abstract
Reflector and light systems include collecting and back
reflecting surfaces that efficiently collect the energy produced by
a light source and redirect the light back through the collecting
surface without restriking the collecting surface or the light
source. The reflected light does not reach the focus for the back
reflecting surface until the light exits the system. A lens-end
bulb may be used as the light source to produce a projected cone of
light that is focused on a target that is positioned in front of
the second focus and a reflected cone of light that is focused on
the same target. In one form of the invention, the back reflecting
surface is eliminated to permit the projected light to be focused
on one target located externally of one end of the system and the
reflected light to be focused on another target located externally
of the other end of the system.
Inventors: |
Parker; Jeffrey R. (Concord,
OH) |
Assignee: |
Lumitex, Inc. (North Royalton,
OH)
|
Family
ID: |
22419200 |
Appl.
No.: |
07/125,323 |
Filed: |
November 24, 1987 |
Current U.S.
Class: |
362/298; 362/346;
362/349; 362/551 |
Current CPC
Class: |
G02B
6/0006 (20130101); G02B 6/4298 (20130101) |
Current International
Class: |
F21V
8/00 (20060101); G02B 6/42 (20060101); F21V
007/00 () |
Field of
Search: |
;362/277,298,299,301,302,304,319,346,347,349,32,19,297 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
119470 |
|
Oct 1919 |
|
GB |
|
763376 |
|
Dec 1956 |
|
GB |
|
Primary Examiner: Lazarus; Ira S.
Assistant Examiner: Cox; D. M.
Attorney, Agent or Firm: Renner, Otto, Boisselle &
Sklar
Claims
What is claimed is:
1. A reflector and light system comprising a reflector assembly
including collector means having a first focus, a light source
positioned substantially at said first focus, and reflector means
having a second focus located externally and forward of said
collector means, said collector means having opening means through
which light is reflected by said reflector means toward said second
focus, said collector means being operative to collect light rays
emitted by said light source and direct such light rays onto said
reflector means, and said reflector means being operative to
redirect such light rays back through said collector means and out
through said opening means, said light source comprising a lens-end
bulb including a lens which projects a cone of light out through
said opening means in said collector means, and said bulb also
produces additional light rays which are emitted radially in the
shape of a conical section onto said collector means which reflects
such additional light rays onto said reflector means and said
reflector means in turn re-reflects such additional light rays
through said collector means and out through said opening
means.
2. The system of claim 1 wherein such conical section of light has
substantially constant stop and start angles which intersect said
collector means.
3. The system of claim 2 wherein said opening in said collector
means has a radius substantially corresponding to the perpendicular
distance from the principal optical axis of said system to a point
on said collector means where the additional ray of light which
defines said start angle and the reflected ray of said stop angle
substantially intersect.
4. The system of claim 1 further comprising a target positioned in
front of said opening means.
5. The system of claim 4 wherein said collector and reflector means
cooperate to cause substantially all of the light rays eminating
from said light source to strike said target at a minimum
acceptance angle.
6. The system of claim 5 wherein the reflected cone of light
intersects the projected cone of light on a plane where the
cross-sectional area of such intersection substantially equals the
cross-sectional area of said target.
7. The system of claim 1 further comprising a target positioned
substantially in the plane of said opening means.
8. The system of claim 1 wherein said target is positioned
substantially where said projected and reflected cones of light
intersect.
9. The system of claim 1 wherein said collector means comprises a
rearwardly facing collecting reflector having a concave collecting
surface, and said reflector means comprises a back reflector
rearwardly spaced from said first focus.
10. The system of claim 9 wherein said back reflector is a cold
mirror.
11. The system of claim 9 wherein said collecting reflector and
back reflector are parabolic dishes.
12. The system of claim 9 wherein said collecting reflector has an
ellipsoidal contour, and said back reflector is in the form of flat
plate.
13. The system of claim 12 wherein said back reflector is in the
shape of a flat circular disc.
14. The system of claim 12 wherein said back reflector is connected
to said collecting reflector by a cylindrical section.
15. The system of claim 12 wherein the ellipsoidal contour of said
collecting reflector intersects said back reflector.
16. The system of claim 1 further comprising lens means disposed in
said opening means in said collector means for focusing both the
projected and reflected light onto a target exteriorly of said
reflector assembly in front of said second focus.
17. The system of claim 16 wherein said lens means has a concave
outer ring portion that refracts the reflected light into a
parallel light beam, and a central portion that refracts the
projected light into a parallel light beam.
18. A reflector and light system comprising a reflector assembly
including collector means having a first focus, a light source
positioned substantially at said first focus, and reflector means
having a second focus located externally of said reflector assembly
forwardly of said collector means, said collector means having
opening means therein for passage of light from said light source,
said light source comprising a lens-end bulb including lens means
which projects a cone of light out through said opening means in
said collector means, and said bulb also produces additional light
rays which are emitted radially in the shape of a conical section
onto said collector means which reflects substantially all of such
additional light rays onto said reflector means, and said reflector
means re-reflects such reflected light back through said collector
means and out through said opening means.
19. The system of claim 18 wherein such conical section of
additional light rays has substantially constant start and stop
angles which intersect said collector means.
20. The system of claim 19 wherein said opening means in said
collector means has a radius substantially corresponding to the
perpendicular distance from the principal optical axis of said
system to a point on said collector means where the additional ray
of light which defines said start angle and the reflected ray of
light of said stop angle substantially intersect.
21. The system of claim 18 further comprising a target positioned
in front of said opening means where said projected and reflected
light intersect.
22. The system of claim 21 wherein said target is the end of a
fiber optic cable.
23. The system of claim 22 wherein said collector and reflector
means cooperate to cause substantially all of the projected and
reflected light to strike said target at a minimum acceptance
angle.
24. The system of claim 23 wherein the reflected light intersects
the projected light on a plane where the cross-sectional area of
such intersection substantially equals the cross-sectional area of
said target.
25. A reflector and light system comprising collector means having
an ellipsoidal contour, said collector means terminating at one end
in a relatively small opening and terminating in the opposite end
in a relatively large opening, a first focus interiorly of said
collector means adjacent said one end, and a second focus
externally of said other end, a light source positioned
substantially at said first focus, said light source comprising a
lens-end bulb including a lens which projects a cone of light out
through said small opening, and said bulb also produces additional
light rays which are emitted radially in the shape of a conical
section onto said collector means which reflects such additional
light rays toward said second focus.
26. The system of claim 25 wherein such cone of additional light
rays has substantially constant start and stop angles which
intersect said ellipsoidal contour of said collector means.
27. The system of claim 25 further comprising a first target
positioned externally of said small opening, and a second target
positioned externally of said large opening.
28. The system of claim 27 wherein said first target is positioned
axially inwardly of said first focus corresponding to where the
cross-sectional area of said first target substantially equals the
cross-sectional area of the projected cone of light passing through
said small opening.
29. The system of claim 27 wherein at least one of said targets
comprises an end of a fiber optic cable.
30. The system of claim 25 wherein said second target is positioned
axially inwardly of said second focus corresponding to where the
cross-sectional area of said second target substantially equals the
cross-sectional area of the reflected cone of light passing through
said large opening of said collector means.
31. A reflector and light system comprising a reflector assembly
including collector means having a first focus, a light source
positioned substantially at said first focus, and reflector means
having a second focus located externally and forward of said
collector means, said collector means having opening means through
which light is reflected by said reflector means toward said second
focus, said collector means being operative to collect light rays
emitted by said light source and direct such light rays onto said
reflector means, and said reflector means being operative to
redirect such light rays back through said collector means and out
through said opening means, said collector means comprising a
rearwardly facing collecting reflector having concave collecting
surface means, and said reflector means comprising a substantially
flat back reflector rearwardly spaced from said first focus.
32. The system of claim 31 further comprising adjustment means for
adjusting the axial position of said back reflector relative to
said collecting reflector to permit proper focusing of light from
different light sources.
33. The system of claim 32 wherein said adjustment means comprises
an axially adjustable threaded connection between said back
reflector and collecting reflector.
34. The system of claim 32 wherein said adjustment means comprises
a peripheral flange on said back reflector in threaded engagement
with an external surface on said collecting reflector.
35. The system of claim 31 further comprising a target positioned
in front of said opening means.
36. The system of claim 35 further comprising external coupling
means surrounding said opening means for supporting said target in
front of said opening means.
37. The system of claim 36 wherein said target comprises a fiber
optic cable, said cable having a cable connector on one end which
is secured in place in said coupling means.
38. The system of claim 37 further comprising filter means for
filtering out undesirable wavelengths.
39. The system of claim 35 further comprising a light pipe for
transmitting light passing through said opening means to said
target.
40. The system of claim 39 wherein said target comprises a fiber
optic cable, said cable having a cable connector on one end which
is secured in place in the axial outer end of said light pipe.
41. The system of claim 40 further comprising filter means within
said light pipe for filtering out undesirable wave lengths.
42. A reflector and light system comprising a reflector assembly
including collector means having a first focus, light source means
positioned substantially at said first, focus, and reflector means
having a second focus located externally of said reflector assembly
forwardly of said collector means, said collector means having
opening means therein for passage of projected light from light
source means, said light source means also producing additional
light rays which are emitted radially onto said collector means
which reflects substantially all of such additional light rays onto
said reflector means, and said reflector means re-reflects
substantially all such additional light rays back through said
collector means and out through said opening means substantially
without striking said light source means.
43. The system of claim 42 wherein the additional light rays that
are emitted radially by said light source means are in the shape of
a conical section having substantially constant start and stop
angles which intersect said collector means.
44. The system of claim 43 wherein said opening means in said
collector means has a radius substantially corresponding to the
perpendicular distance from the principal optical axis of said
system to a point on said collector means where the additional
light rays which define said start and stop angles substantially
intersect.
45. The system of claim 42 wherein said collector means comprises a
rearwardly facing collecting reflector having concave collecting
surface means, and said reflector means comprises a substantially
flat back reflector rearwardly spaced from said first focus.
46. A reflector and light system comprising a reflector assembly
including collector means having a first focus, a light source
positioned substantially at said first focus, and reflector means
having a second focus located externally and forward of said
collector means, said collector means having opening means through
which light is reflected by said reflector means toward said second
focus, said collector means being operative to collect light rays
emitted by said light source and direct such light rays onto said
reflector means, and said reflector means being operative to
redirect such light rays back through said collector means and out
through said opening means, said collector means comprising a
rearwardly facing collecting reflector having a concave collecting
surface, and said reflector means comprising a back reflector
rearwardly spaced from said first focus, said back reflector having
an axial hole therethrough having a minimum diameter that will
permit said light source including a light source holder to pass to
facilitate positioning and removal of said light source without
interfering with light collection or projection.
Description
BACKGROUND OF THE INVENTION
This invention relates generally, as indicated, to a reflector and
light system, and more particularly, to such a system which
provides a relatively compact, optically efficient and cost
effective light source for a target, especially a relatively tight
target such as a fiber optics light pipe or the like that requires
the light to strike the target at a minimum acceptance angle.
Because of the increased use of fiber optics light pipes and the
like to transmit light, there is an increasing need for a more
efficient light source for the transmitted light. Fiber optics
light pipes generally consist of one or more strands of glass or
plastic fibers which may be used for a wide variety of
applications, including inspection lighting, ultraviolet curing,
phototherapy, instrumentation, clean rooms, and fiberscopes and the
like.
It is generally known from U.S. Pat. No. 4,241,382 to provide an
illuminator in the form of a light bulb having a fiber optics
coupler as an integral part of the envelope. The bulb is provided
with a combination of ellipsoidal and spherical mirrors which
direct the light through an optical window to a fiber optics light
pipe or the like. To facilitate trapping of the light in the
optical fibers, the light may be caused to emerge from the optical
window at angles equal to or less than the critical angle of the
fibers.
The critical angle is the maximum angle of incidence of the light
rays striking the fibers that will experience total internal
reflection within the fibers. Therefore, all of the light that is
focused on the fibers must strike the fiber ends at angles equal to
or less than the critical angle or that portion of the light which
does not will not be transmitted by the fibers.
Although the illuminator of the aforementioned U.S. Pat. No.
4,241,382 accounts for the critical angle, such illuminator does
not effectively account for the attenuation of the light in the
fibers. When light is transmitted through an absorbing medium, the
irradiance decreases exponentially with the distance of
transmission. The distance light must travel within optical fibers
is inversely proportional to the cosine of the angle that the light
enters the fibers. Therefore, a light source that directs light at
a target at a minimum acceptance angle would be optimal.
To achieve a small acceptance angle with the illuminator of U.S.
Pat. No. 4,241,382 would require an increase in the distance
between the filament and the optical window, which has the
objection that the overall dimensions of the illuminator would have
to be increased exponentially. Also, increasing such distance would
cause the distance between the filament and the ellipsoidal surface
to decrease. As the filament nears the ellipsoidal surface, defocus
occurs causing a greater percentage of the light to be reflected at
non-collectable angles or reflected back into the filament.
Therefore, there is a minimum average acceptance angle that this
particular illuminator can produce.
British Patent Specification No. 763,376, published Dec. 12, 1956,
discloses a multi-reflector system that addresses some of these
problems by providing a rearwardly facing reflector that reflects
the light back onto a forwardly facing reflector that in turn
reflects the light forwardly in a parallel beam. However, this
system has the drawback that the focal point for the forwardly
facing reflector is within the reflector system itself. Also, the
forwardly facing reflector reflects the light as a parallel beam,
which makes it difficult to focus the light on a relatively tight
target outside the reflector, and the light is reflected back
through the light source which blocks out a large percentage of the
light before it reaches the target.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is a principal object of this
invention to provide reflector and light system that provides a
relatively compact, optically efficient and cost effective light
source for a target.
Another object is to provide such a system that efficiently
collects and focuses substantially all of the light emitted from
the light source onto a target at a minimum acceptance angle.
Still another object is to provide such a system including a
collecting reflector and back reflector which collect and redirect
the reflected light back through the collecting reflector to keep
the overall package size to a minimum.
A further object is to provide such a system in which the reflected
light forms a cone of light that passes back through the collecting
reflector with minimum reflected light striking the light source or
restriking the collecting reflector.
Yet another object is to provide such a system which produces a
projected cone of light that is focused on a target positioned at a
distance from the light source where the cross sectional area of
the projected light substantially equals that of the target.
Yet another object is to provide such a system in which the
reflected cone of light also strikes the target at the plane where
the cross-sectional area of the reflected cone substantially equals
the cross-sectional area of the target.
These and other objects may be achieved by providing in one form of
the invention a system including a rearwardly facing collecting
reflector for collecting substantially all of the reflected light
eminating from a light source located substantially at the focal
point of the collecting reflector, and a forwardly facing back
reflector which receives the reflected light from the collecting
reflector and redirects the light back through the collecting
reflector onto a target externally of the reflector.
In accordance with one aspect of the invention, the light source is
a lens-end incandescent bulb that projects a cone of light through
an axial opening or window in the smaller end of the collecting
reflector and focuses the projected light on the target located
externally of the reflector system at the point where the
cross-sectional area of the projected cone substantially equals
that of the target.
Further in accordance with the invention, the additional light
produced by the lens-end bulb that is not directly projected onto
the target is emitted radially in the shape of a conical section
rotated about the principal axis of the bulb and reflected by the
collecting reflector surrounding same. This conical section of
additional light has substantially constant start and stop angles
which intersect the reflecting surface of the collecting reflector.
The additional non-projected light is reflected onto the back
reflector which in turn re-reflects the additional non-projected
light back through the collecting reflector and focused on the
target, preferably substantially without striking the light source
or restriking the collecting reflector. Also, the reflector system
is desirably designed so that the reflected cone of light strikes
the target at the plane where the cross-sectional area (diameter)
of the reflected cone substantially equals that of the target, and
the outer periphery (surface) of the reflected cone also intersects
the outer periphery (surface) of the projected cone.
Further in accordance with the invention, the collecting reflector
may be an ellipsoidal section and the back reflector a flat
circular disc with a central hole of a size to permit the light
source and holder therefor to pass.
Also in accordance with the invention, the back reflector may be
axially adjustable relative to the collecting reflector to allow
for proper focusing of the light when bulbs and/or lenses of
different sizes and shapes are used.
In accordance with another aspect of the invention, the reflector
assembly may be vented to provide for internal cooling.
Further in accordance with the invention, a suitable coupling may
be provided around the light discharge opening or window in the
reflector assembly for supporting the target at the desired
distance exteriorly of the assembly.
Still further in accordance with the invention, a light pipe may be
utilized to transmit the light rays exteriorly of the reflector
assembly to a target located a desired distance beyond the
reflected focal point.
In another form of the invention, both the collecting reflector and
back reflector may be parabolic surfaces, with the light source
placed substantially at the focal point of the collecting reflector
and the target placed axially inwardly of the focal point of the
back reflector where the cross-sectional area of the reflected cone
of light from the back reflector substantially equals the
cross-sectional area of the target.
In accordance with another aspect of the invention, a lens may be
mounted at the smaller open end of the collecting reflector to
refract both the projected and reflected cones of light into a
parallel beam of light which is focused on the target.
In accordance with still another aspect of the invention, the back
reflector may be eliminated and the reflector system utilized to
focus the light rays on two targets, one located externally of each
end of the collecting reflector.
Also in accordance with the invention, the collecting reflector may
be elongated in the transverse direction to accommodate a line
filament lamp located substantially at the focal point of the
collecting reflector, and the target may be an elongated optical
window adjacent the smaller end of the collecting reflector. Such a
system would be especially useful in applications where a highly
efficient uniform line of light is desired such as in photocopy
machines, or for illuminating ribbon fiber optic cables or reading
identification cards and the like.
In accordance with still another aspect of the invention, the light
source may be a light emitting diode cast as part of the collecting
reflector and back reflector to form a single modular unit, and the
collecting and back reflectors coated with a suitable reflective
material.
To the accomplishment of the foregoing and related ends, the
invention, then, comprises the features hereinafter fully described
and particularly pointed out in the claims, the following
description and the annexed drawings setting forth in detail
certain illustrative embodiments of the invention, these being
indicative, however, of but several of the various ways in which
the principles of the invention may be employed.
BRIEF DESCRIPTION OF THE DRAWINGS
In the annexed drawings:
FIG. 1 is a schematic longitudinal sectional view through one form
of reflector and light system in accordance with this
invention;
FIG. 2 is an enlarged schematic illustration of a lens-end bulb
which may be used as the light source for the system of FIG. 1;
FIG. 3 is a side elevation view of a modified form of reflector and
light system in accordance with this invention;
FIG. 4 is a fragmentary longitudinal section through the system of
FIG. 3;
FIG. 5 is a fragmentary longitudinal section through another
modified form of reflector and light system in accordance with this
invention;
FIG. 6 is a schematic longitudinal sectional view of another form
of reflector and light system in accordance with this
invention;
FIG. 7 is an enlarged longitudinal sectional view through a lens
which may be used with the system of FIG. 6;
FIGS. 8 and 9 are schematic longitudinal sectional views through
other reflector and light systems in accordance with this
invention;
FIGS. 10 and 11 are schematic perspective views of still two more
reflector and light systems in accordance with this invention;
and
FIGS. 12 and 13 are schematic side elevation views of still two
more reflector and light systems in accordance with this
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in detail to the drawings, and initially to FIG. 1,
there is schematically shown a preferred form of reflector and
light system 1 in accordance with this invention including a
reflector assembly 2 for collecting light rays emitted from a light
source 3 mounted within the reflector assembly and focusing such
light rays on a relatively tight target or light receiving area T
outside the reflector assembly. In the embodiment illustrated in
FIG. 1, the reflector assembly 2 includes a rearwardly facing
collecting reflector 4 having an ellipsoidal contour with respect
to a focal point F, and a forwardly facing back reflector 5 in the
form of a flat circular disc extending perpendicular to the
principal optical axis A and rearwardly spaced from the focal point
F.
Also in the embodiment shown in FIG. 1, the light source 3 is a
lens-end bulb 6 located substantially at the focal point F of the
collecting reflector 4 with the bulb lens 7 projecting a cone P of
light out of the system 1 through an opening 8 in the smaller end 9
of the collecting reflector. As schematically shown in greater
detail in FIG. 2, the projected cone P of light increases in size
with distance from the bulb and is centered about the principal
optical axis. The projected cone P is focused on the target T which
may, for example, be the end of a fiber optics cable which is
circular in shape and located on a plane perpendicular to and
centered about the original optical axis A. Also, the target T is
preferably positioned at a distance from the bulb 6 where the
cross-sectional area of the projected light cone P substantially
equals the cross-sectional are of the target which could be at the
opening 8 but is preferably forwardly spaced some distance
therefrom as schematically illustrated in FIG. 1.
Substantially all of the other light rays from the bulb 6 that are
not directly projected out through the opening 8 in the collecting
reflector 4 are emitted radially in the shape of a conical section
R rotated about the principal optical axis. Conical section R has a
constant start and stop angle represented by the rays labeled d and
x in FIGS. 1 and 2. The collecting reflector 4 reflects
substantially all of these additional light rays (hereafter
referred to as reflected cone R of light) onto the back reflector 5
which in turn further reflects the reflected light back through the
opening 8 in the small end of the collecting reflector 4 and
focuses such reflected light on the target T.
The optimum radius of opening 8 is the perpendicular distance from
the principal optical axis A to the point on the collecting
reflector where ray d and reflected ray z intersect. The elliptical
shape of the collecting reflector 4 and the position of the back
reflector 5 determine the position of the second reflected focal
point F' and the average acceptance angle of the light rays
striking the target T. The reflector system is designed such that
substantially all of the light rays uniformly strike the target at
a minimum acceptance angle and the reflected cone of light
intersects the projected cone of light on a plane axially inwardly
of the reflected focal point F' where the cross-sectional area
equals that of the target. Expressed mathematically, the target T
is preferably located at a distance L from the bulb 6 defined by
the equation L=0.5 (Diameter target-Diameter lens)/(Tan 0) where
the angle 0 is the angle between the lens diameter and the exterior
of the projected cone P of light (see FIG. 2).
The back reflector 5 may be connected to the collecting reflector 4
as by means of a cylindrical section 10 extending between the
collecting reflector and outer diameter of the back reflector as
shown in FIG. 1. Cylindrical section 10 commences rearwardly of the
point where the stop angle represented by the ray x hits the
collecting reflector 4, whereby such cylindrical section does not
have any effect on the efficiency of this system.
If desired, a cold mirror may be used for the back reflector 5 to
provide for the removal of a high percentage of the infrared
wavelengths of light and cause reflection of others, including
particularly the optical wavelengths, etc.
Likewise, the collecting reflector 4 may be made of a suitable
dichroic material of known type to allow certain bandwidths of
energy such as infrared wavelengths to pass through the collecting
reflector and cause reflection of others such as optical
wavelengths, etc.
An axial hole 11 may be provided in the back reflector having a
minimum diameter that will permit the bulb 6 and bulb holder 12 to
pass to facilitate bulb positioning and removal and to provide a
bulb support that does not interfere with light collection or
projection. Alternatively, the bulb could be supported from and
through the side of the collecting reflector rather than through
the back reflector as shown. However, such a side support would
necessarily block some of the light rays, making it less
desirable.
In FIGS. 3 and 4 the back reflector 5 is shown as having a
rearwardly extending hub 13, with a set screw 14 extending radially
therethrough for frictionally engaging the bulb holder 12 to
releasably retain the light source 3 in position within the
reflector assembly 2. Also, the back reflector 5 is shown as being
provided with an external flange portion 15 having a threaded
connection 16 with the exterior of the collecting reflector 4 to
permit limited axial adjustment of the position of the back
reflector relative to the collecting reflector. This has the
advantage that light sources and/or lenses of different sizes and
shapes may be used with the same reflector assembly, in that
adjustment of the position of the back reflector relative to the
collecting reflector allows for proper focusing of the light from
such different light sources and/or lenses. Also, the threaded
flange 15 on the back reflector 5 may be substantially open as by
providing circumferentially spaced slots 1 therein to allow for
cooling of the interior of the reflector assembly through such
openings without interfering with the internal reflection of light
as further shown in FIGS. 3 and 4.
If desired, a suitable coupling or sleeve 18 may surround the
reflector opening 8 to support the target T, in this case the end
of a fiber optic cable, at the desired distance exteriorly of the
collecting reflector. When the target is a fiber optic cable, the
cable may have a cable connector 19 on such end which may be
inserted into the connector coupling 18 and secured in place as by
using a suitable epoxy or the like. Also, a filter 20 may be placed
at the inner end of such cable to filter out any undesirable
wavelengths.
Moreover, a light pipe 22, shown in FIG. 5, may be used to transmit
the light rays passing through the opening or window 8 to the
target T which may be located a desired distance beyond the
reflected focal point. The interior surface of the light pipe 22,
like that of the reflector assembly, may be coated with a suitable
reflective material. The light pipe 22 acts as a support for the
target, and scrambles the light rays to produce a more uniform
target spot with minimum loss. The length of the light pipe is
determined by the light ray angles and the desired amount of
diffusion of the light on the target. When the target is a fiber
optic cable, a cable connector 19, similar to that shown in FIGS. 3
and 4, may be attached to the end of the cable and inserted in the
outer end of the light pipe and secured in place using a suitable
epoxy. Also, a filter 20, similar to that previously described, may
be placed within the light pipe at the inner end of the cable to
filter out undesirable wavelengths.
Although the light pipe is shown in FIG. 5 as being integral with
the reflector assembly, it should be understood that the light pipe
could be formed separately from the reflector assembly if desired.
Also, the light pipe could be mounted in spaced relation from the
reflector assembly a distance at least corresponding to the
location of the second reflected focal point.
Also, if desired, a lens 25 may be disposed within the smaller open
end 8 of the collecting reflector 4 to redirect both the projected
and reflected cones P and R of light into a parallel beam of light
which is then focused on the target T as schematically shown in
FIG. 6. The lens 25 itself is shown in greater detail in FIG. 7 as
having a concave outer ring portion 26 that refracts the reflected
rays R into a parallel beam and a flat or convex central portion 27
that also refracts the projected rays P into a parallel light beam.
If such a lens 25 is used, the position and diameter of the target
T will have to be changed accordingly. Otherwise, the details of
construction and operation of the reflector and light system 1
shown in FIG. 6, are substantially the same as that shown in FIG.
1.
If desired, the back reflector of FIGS. 1 through 6 could be
removed from the system as schematically shown in FIG. 8, in which
event the system 30 could be used to focus the projected and
reflected light rays P and R on two different targets. One of the
targets T would still be located directly in front of the lens bulb
6 at the point where the cross-sectional area of the projected cone
P of light substantially equals that of the target. The other
Target T' would be placed just before the second focal point F' of
the collecting reflector 4 where the cross-sectional area of the
reflected cone R of light off the collecting reflector
substantially equals that of the other target T'. Of course, in
that event, both the small and large ends of the collecting
reflector would be open at 8 and 31 to permit the projected light P
to be focused on the first target T and the reflected light R to be
focused on the second target T'.
In FIG. 9 there is shown another form of reflector and light system
32 in accordance with this invention in which both the collecting
reflector 33 and back reflector 34 which comprise the reflector
assembly 35 are parabolic dishes, and the light source 36 is placed
substantially at the focal point F of the collecting reflector and
the target T is placed just before the focal point F' of the back
reflector 34 which is located along the principal optical axis
outside the smaller open end 37 of the collecting reflector 33.
Here again, the light source 36 may be a lens-end bulb with the
lens projecting a cone of light out of the system through the
opening 37 in the smaller end of the collecting reflector and
focused on the target T and the additional light reflected by the
collecting reflector onto the back reflector and then off the back
reflector back through the collecting reflector and out the opening
37 and focused on the target T, similar to the system 1 previously
described. Such a reflector assembly 35 is desirably designed so
that all of the reflected light passes back through itself and does
not strike the bulb 36 or restrike the collecting reflector 33,
similar to the reflector designs previously described.
In still another form of reflector and light system 38 shown in
FIG. 10, the collecting reflector 39 is elongated in the transverse
plane to accommodate a line filament lamp 40 located substantially
at the focus F of the collecting reflector which extends
substantially the full width thereof. Also, the back reflector 41
may be a flat rectangular mirror whose focus is outside a long
narrow optical window 42 extending substantially the full width of
the smaller open end 43 of the collecting reflector. Such a
reflector and light system 38 may be used in any application where
a highly efficient uniform line of light is desired, such as in
photocopy machines, or for illuminating ribbon fiber optic cables
or reading identification cards and the like.
Yet another form of reflector and light system 45 in accordance
with this invention is schematically shown in FIG. 11. In this
embodiment, the light source (not shown) may be a light emitting
diode, and the collecting reflector 46 and back reflector 47 may be
cast in the desired contoured shape as a single modular unit with
the back reflector 47 connected to the collecting reflector 46 in
spaced relation therefrom as by means of a generally U-shaped
flange 48 extending between the exterior surfaces thereof. The
collecting reflector 46 may have an ellipsoidal shape and the back
reflector 47 a substantially flat rectangular shape as shown.
Moreover, both reflectors 46 and 47 may be coated with a suitable
internal reflective material to reflect the light from the light
emitting diode back through the collecting reflector and out
through the smaller open end o window 49 of the collecting
reflector and focused on a target T, for example, a fiber optic
cable, located externally of the reflector assembly 50. The shape
of the two reflectors 46, 47 will be determined by the size and
shape of the target. The advantage of this particular system is
that it can be produced inexpensively in large quantities.
In FIG. 12 there is schematically illustrated still another form of
reflector and light system 55 in accordance with this invention
which is a form of electroluminescent diode cast as part of a solid
unit including both a collecting reflector 56 and a back reflector
57. This unit can produce both visible and infrared light. Visible
units incorporate gallium phosphorous or gallium aluminum chips
cast into the center of the unit as a light source. Such a diode
emits light along the junction region and also over the top surface
of the junction. The contacts 58, 59 are shaped such that light is
emitted in a forward direction and do not interfere with light
collection or projection.
In the particular embodiment shown in FIG. 12, the collecting
reflector 56 is in the shape of an ellipsoidal section rotated
about the principal optical axis and the back reflector 57 is in
the shape of a round circular disc centered about the same axis.
The collecting and back reflectors 56, 57 may be joined by a
cylindrical section 60 similar to that shown in FIG. 1. Also, all
three of these surfaces 56, 57 and 60 may be deposited or coated
with an internally reflective substance such that total internal
reflection occurs.
Unit 55 also includes a front window 61 in the shape of a sloped
washer 62 with a parabolic or elliptically shaped hub 63 at its
center. The washer 62 and hub 63 surfaces are centered about the
principal optical axis, and if the slopes of the rotated washer 62
surfaces were extended, they would intersect the focal point F
which corresponds to the first focal point of the collecting
reflector 56 and the focal point of the front hub 63. While the
sloped washer 62 is shown as being substantially flat, it should be
understood that such washer may also be curved, or of a convex or
concave shape, depending on the desired results.
Typical light ray paths are also schematically shown in FIG. 12.
Rays G and H are emitted so that they first strike the front hub
63, which causes them to be refracted in such a manner that they
are transformed either into a parallel beam or focused to the size
and shape of target T as desired. Ray I is emitted in a direction
such that it first strikes the collecting reflector 56 and is
reflected thereby onto the back reflector 57 which re-reflects the
ray toward the optical window 61. Upon striking the washer section
62 of the optical window, ray I is refracted so that it also
becomes a parallel ray or is focused to the size and shape of the
target.
This type of system can also be provided with a front window 61'
having a flat washer section 65 as shown in FIG. 13 instead of a
sloped washer section 62 as shown in FIG. 12. Also, the ellipsoidal
section of the collecting reflector 56' may be extended toward the
rear to intersect the back reflector 57' as further shown in FIG.
13. Otherwise, the details of construction and operation of the
system shown in FIG. 13 are substantially the same as that shown in
FIG. 12, and accordingly, the same reference numerals followed by a
prime symbol are used to designate like parts.
A system of the type shown in FIGS. 12 or 13 may be but need not be
epoxied directly to the end of a fiber optic cable. Also, the light
source may be used to produce both visible and/or infrared energy,
and may include more than one light emitting junction which does
not have to be located at the focal point of the ellipsoidal
section 56 or 56'.
From the foregoing, it will now be apparent that the various
systems of the present invention disclosed herein provide a
relatively compact, optically efficient and cost effective light
source for a target such as a fiber optic cable. However, it should
be understood that the target may be other light receiving areas
than a fiber optic cable including, for example, a lens, filter,
hot mirror, cold mirror or the like. Also, while it is preferred
that the target be generally circular, it may be of other shapes as
well.
Moreover, while the light source is preferably a lens-end filament
lamp, it will be apparent that other means for producing light
having variety of different voltage and current requirements may be
used, including, for example, a light emitting diode, an arc lamp,
a sodium vapor lamp, and a high intensity discharge lamp. Also, the
collecting and back reflectors may be made out of any suitable
materials such as plastic, glass or metal that can be formed to the
proper shape or coated. Furthermore, the reflecting surfaces may be
elliptical, parabolic, circular, flat, compound, multi-mirror or
any combination that will direct the light back through the
collecting reflector and focus on the target. Other modifications
may also be necessary for a particular application including the
use of cooling fins, mounting brackets, light source holders,
coatings and filters to aid in the transmission and absorbtion of
certain frequencies of electromagnetic radiation.
Although the invention has been shown and described with respect to
certain preferred embodiments, it is obvious that equivalent
alterations and modifications will occur to others skilled in the
art upon the reading and understanding of the specification. The
present invention includes all such equivalent alterations and
modifications, and is limited only by the scope of the claims.
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